A) DUALISM

i. Substance Dualism.  The mind and the body are different types of substance irreducible one to the other.  Substance dualists often disagree on the nature of the soul (the substance of the mind).  For example, Descartes thought that the soul is unextended and not in space; Clarke, by contrast, thought it extended and in space.

First Argument for substance dualism

1. The existence of my body is dubious (I might be a disembodied spirit).
2. The existence of my mind is not dubious (I know that I'm conscious).
3. So my mind is not  identical to my body.

NOTE: This argument is an application of the principle that if X and Y are one and the same thing, then X and Y have the same properties. So if X and Y have different properties, then they cannot be one and the same thing.
Problem: the principle may not be used when we're dealing with intensional sentences (e.g., sentenced of the form "I doubt that ..." or 'I believe that...".. Consider the following argument:
• The existence of a murderer is dubious (perhaps it was a case of suicide)
• The existence of the suspect is not dubious (here he is, in front of us)
• So, the suspect is not the murderer
All of the premises of this argument may be true, and yet its conclusion may be false. It just turns out that it wasn't suicide and that the suspect is the murderer.  So the argument is invalid.  So, the original argument is invalid as well.

Second Argument for Substance Dualism

1. I can imagine or conceive of my mind existing without my body.

For example, suppose you are hit your head, and when you come to consciousness everything is dark and you can't  feel your body.  You're not sure: have you been blinded and paralyzed? Or are you now dead, and this is what it feels like to exist without a body? Here you are thinking about a situation in which you exist without a body, and wondering whether that situation is the one you are in.
2. Since I can conceive of my mind existing without my body, it must be possible for my mind to exist without my body.
3. Hence, my mind must be a distinct anmd separate thing from my body.

Problems:
Does conceivability entail possibility?
It's important to distinguish between the following three claims:
1. It is possible for me to exist without this body
2. It is possible for me to exist without any body
3. As a matter of fact, I am partly made up of something separate and distinct from my body
(1) might be true without (2) being true (teletransportation).  Moreover, (2) might be true without (3) being true (although I could exist disembodied, as a matter of fact I am wholly made up by my body without any disembodied parts). The original argument may conclude to (1) or perhaps (2), but not to (3).  But (3) is what is required for substance dualism.

Problems for Substance Dualism

How do our souls causally interact with our bodies?  Why is my mind so radically affected by what goes on in my body?
 
 

ii. Property Dualism.
This theory makes two main claims

• there isn’t  a thinking substance distinct from the body (brain).  Hence, substance dualism is false.
• However, the body’s (brain’s) mental properties are non-material in the sense that they cannot in principle be explained solely in terms of physical properties. Hence, the mental requires a science not reducible to physical science.

1. the mind is an epiphenomenon, caused by biological events
2. it has no causal influx on the body.
3. Hence, the brain events which cause mental events also cause the actions which we naively think are caused by these mental events.
4. So, the mind is a mere inefficacious accompaniment.

B) MATERIALISM.
There are two main varieties of materialism with respect to the mind/body problem, Identity Theory, and Eliminativism

i. Identity theory.

• Mental states are physical states of the brain.  For example, pain is such and such brain state.

NOTE: The claim that pain is such and such a state is not knowable a-priori, but is the result of an a-posteriori discovery.  In particular, "Being in pain" does not mean "being in such and such brain-state" much in the same way in which "being water" doesn't mean "being H2O."
• Basic acceptance of folk-psychology and the belief that most folk psychological notions can be reduced to neuroscience notions, as thermodynamics to statistical mechanics.

ii. Eliminativism.
Mental states do not exists much in the same way in which supernatural powers or ghosts don't exist. In particular, the explanatory power of folk psychology is minimal: it tells nothing about why we sleep, of how memory works, of hemineglect,  alexia without agraphia (write well, but unable to read), etc..  It is so wrong that it will eventually be completely abandoned, much in the same way in which the caloric or flogiston theories have been abandoned without being reduced to statistical mechanics or chemistry.
 

C) THEORIES neutral between dualism and monism, but with materialist leanings.

 i. Behaviorism

In 1950, Alan Turing proposed that if one carries on remote conversations with a computer and another human, and cannot determine which is which, then tthe computer counts as intelligent. This has come to be known as the Turing Test for computer intelligence.  Although the Turing Test can be undrestood in different ways (as providing good evidence for intelligence, or as providing a certain criterion for intelligence), if one believes that the capacity to pass the test is what it is to be intelligent, then one is a behaviorist about intelligence.  That is, a behaviorist about intelligence believes that all there is to being intelligent is being disposed to respond appropriately to certain kinds of stimulations, in this case, the questions involved in the remote converstions.  More broadly, a behaviorist about some mental state says that all there is to being in that state is being disposed to behave in specific ways in response to specific sorts of stimulation.

• NOTE the following about dispositions:  A disposition is a property like being fragile, or being soluble. A glass can be fragile even though it never breaks. It merely has to be such that it would break, if it were struck in certain ways or if it were dropped from a modest height.
• The manifestation of the disposition is the breaking, dissolving, etc. Usually, there will be some underlying facts about the object in virtue of which it has the disposition.
• These are the disposition's categorical basis.
• A disposition might have different categorical bases in different objects: fragility has one categorical basis in crystal wine glasses and a different categorical basis in soap bubbles.

Problems for behaviorism

• we think it's possible for someone to be in pain without engaging in pain behavior.
• We seem to have direct access at least to some of our own mental life: we don't always need to observe our behavior to know how we're feeling.
• How one behaves depends on all the mental states one has.  Any plausible connection between mental states and behavior will have to invoke many mental states in explaining the behavior: you are disposed to look at the Hawaii brochures if you havn't seen many already; you're disposed to pack tour luggace if you don't believe that plane will crash or you won't be fired if you go, or....So, it seems impossible for the behaviorist to define any one mental state until he has already defined lots of other mental states. So the behaviorist's account will never get off the ground.

 ii. Functionalism

Suppose we want to explain what the different parts of a car are, and that we have a theory of how the different parts of a car interact with each other,
and with things our audience already understands, like air and gasoline. The theory might look something like this:

Car Theory: ...and the carburetor mixes gasoline and air and sends the mixture to the ignition chamber, which in turn.....and that  makes the wheels turn.

We can now define what it is to be a carburetor and an ignition chamber as follows:
 

A carburetor = that thing x which mixes gasoline and air and sends the mixture to another thing y, which in turn...and that makes the wheels turn.

An ignition chamber = that thing z such that there's another thing w , and w mixes gasoline and air and sends the mixture to z, which in turn...and that makes the wheels turn.

In other words, we explain what a carburetor is in terms of how it interacts with ignition chambers and with other things. Notice that we've explained what a carburetor and an ignition chamber are in terms of the causal roles they play, as specified in our Car Theory.  So, any pair of things which play the appropriate causal roles count as a carburetor and an ignition chamber. The details of their physical construction are not important. To be a carburetor, it doesn't matter what you're made out of; only that you do the right job. (The same goes for ignition chambers.)

The basic idea of functionalism is to do the same with respect to the mind.  Suppose we have a theory about how our various mental states are causally related to each other, and to input and output:
 

Mental Theory: ...and pain is caused by pin pricks, and pain causes worry and the emission of loud noises, and worry in turn causes brow-wrinkling...

Assuming that our audience already understands things such as various sorts of sensory stimulation, and behavioral output, we can now define what it is to be in pain, and to be worried, as follows:
 

A person is in pain = there's x such that there's a y, ... and x is caused by pin pricks, and x causes y and the emission of loud noises, and y in turn causes brow-wrinkling..., and the person has x.

A person is worried = there's a z such that there's a w, ...and w is caused by pin pricks, and w causes z and the emission of loud noises, and z in turn causes brow-wrinkling... , and the person has z.

The functionalist thinks that all of our mental states can be defined in this way. Anything which has states playing those causal roles counts as having a
mind. Whenever such thing is in the first of those states, it's in pain, and when it's in the second of those states, it's worried. It does not matter what the intrinsic make-up of those states is. In humans, they are certain kinds of brain states. In Martians, they would likely be different sorts of states. In an appropriately programmed computer, they would be electronic states. These would be different physical realizations of the same causal roles. The functionalist identifies our mental states with the causal roles they play. How those roles are realized is not important.  In this respect, the science of the mind is methodologically autonomous from physical sciences, just as software is autonomous from hardware.
The functionalist thinks that minds and mental processes are exactly analogous to software and to the changes that a piece of software undergoes as it's running. So long as there's some hardware with some internal states that stand in the right causal relations to each other and to input and output, you've got a mind. A line of reasoning often offered in support this view is the following.  At some level of description, the brain is a device that receives complex inputs from the sensory organs and sends complex outputs to the motor system. The brain's activity is well-behaved enough to be specifiable in terms of various (incredibly complicated) causal relationships, just like a very complex computer program.

Broadly speaking, there are two main varieties of functionalism, depending on the sort of mental theory one uses to define the functional roles:

1. common-sense (analytic) functionalists say that the theory is an a priori theory, made up of platitudes about our mental states that everyone who has the concepts of pain, belief, and so on, tacitly knows, or at least, is in a position to recognize as true.
2. Scientific (empirical) functionalist says that the theory is an a posteriori theory, which we only learn as a result of scientific investigation of how our minds work

1. The Inverted Spectrum
Many experiences have two different kinds of features: representational features (For instance, your visual experience may represent that there is something red in front of you), and qualitative features (There is "something it is like" to have them).  So, if you suffer from Daltonism, my seeing a green square and your seeing the same green square have the same (or similar) representational features, but different qualitative features (you see a shade of grey while I see green).  By qualia one means the qualitative features of experiences, what's like to have them.
Suppose now that objects we both call green look to me the way objects we both call red look to you. Suppose also that mentally we are functionally equivalent. Still, there's a big difference which functionalism cannot capture: my quale of what we call 'green' is red; yours is green. So, functionalism cannot give a full account of the mind: it leaves out qualia.
Replies:

• The assumption that we are functionally identical is unwarranted; if there are differences in qualia, there will be some functional differences as well.
• Adopt a combination of functionalism and identity theory: qualia cannot be given a purely functional account but can be explained in terms of the experiences' neurophysiological features. For example, one could be a functionalist about propositional attitudes and the representational features of experience while being an Identity Theorist about the qualitative features of experience.

ii. Searle's Chinese Room  (see essay)